There is a need, particularly in the telecommunications industries, for a back up power source to maintain operations when the primary power source shuts down. These systems generally comprises a plurality of valve regulated lead acid batteries (VRLA) generally of a two volt size which are typically connected in series in various numbers, for example 24, to provide or define a 18 volt system. These batteries are typically constructed of polypropylene jars which is a relatively soft material similar to milk jugs and a cover mounting the leads connected to the jar by a seam. These jars generally require an exterior shell for protection as well as pressure control. It has been found that without compression, these batteries tend to bulge thereby diminishing capacity.
In accordance with a known prior art system, the batteries are stored or placed in multi-cavity modules or trays which are stacked, one on top of the other and secured to one another to provide an array of assembled trays and batteries totaling the requisite number for a given system such as 24 batteries for a 48 volt system.
An important criteria for systems of this type is that the support structures function to support the heavy loads and be reliable particularly in times of crises. These prior systems have certain disadvantages and draw backs. For example, batteries are installed in the modules at the battery plant or factory. Typically, a three battery module may weigh about 800 lbs. These trays are therefore rather bulky and difficult to handle at the installation site. Further, the module pockets, in some instances, are oversized relative to the battery and require the use of shims to snugly position the batteries in the module pockets. The batteries are typically placed in the modules before the final charge creating pressure between the battery and the module. Accordingly, when the batteries swell, if there is need for the installer to remove the batteries, the batteries are usually gripped by the posts which can cause battery damage. Further, it has been found that the interconnected modules are not always as stable as they should be and do not satisfy the criteria for supporting heavy loads in time of seismic crises.
Summarizing the disadvantages of the presently known systems, it has been that cell damage results by overstressing the post seals when installers handle the batteries by the posts, especially during extraction of cell and lifting thereof.
Other adverse affects of extraction of cells from the modules or trays include exposure of the jars to the ambient environment and potential puncture. Further, extraction can result in jar to cover seam damage during reinsertion of the cell into the modular trays. Further, in some instances, the jars are shimmed in the trays to maintain pressure. These shims are inserted prior to jar bulging and once the jar bulges, it is difficult to extract the cell from the trays and even more difficult to reinsert them. Often the shim is not reused resulting in lose of pressure and thus diminishing capacity.